Miley Cyrus parties with a unicorn

The former 'Hannah Montana' star was thrilled with the celebration thrown by close friend Kelly Osbourne at Beacher's Madhouse in the Hollywood Roosevelt Hotel on Tuesday (22.11.11).

Miley - who turned 19yesterday (23.11.11) - tweeted: Can't thank @MissKellyO for the best partyyyy ever! i loveeeee you! Let's just say there was a unicorn in the lobby! (sic)"

The 'unicorn' was a horse with a horn strapped to its head.

Miley enjoyed her party so much, she didn't leave until the early hours of the morning.

A source told Us Weekly magazine: "Her mom Tish went, and so did her boyfriend Liam [Hemsworth]. The group was up until 3am just dancing up a storm and having fun."

Kelly - who befriended Miley when they worked on the as-yet unreleased movie 'So Undercover' together - previously pledged to make her pal's party the "sickest thing ever".

She said: "It's intimate, but it's going to be the sickest thing she's ever seen in her life. Although I see her on the same level mentally as me, I also realize that Miley's 19 and she deserves to still have fun.

"Because that girl has so much pressure on her and has worked her ass off her entire life that I think a lot of the time people forget that she deserves to have fun too. So that was my mission for her, to make her birthday the best day ever. I've got all sorts of madness and craziness planned."